Electrocoating applications

The largest industrial use of ultrafiltration is the recovery of paint from water-soluble coat bases (primers) applied by the wet electrodeposition process (electrocoating) in auto and appliance factories. Many installations of this type are operating around the world. The recovery of proteins in cheese whey (a waste from cheese processing) for dairy applications is the second largest application, where a... 

Other types of equipment that can yield even higher efficiency values are roller and flow coating machines (90 to 98%) and electrocoating systems (90 to 99%). Roller and flow coating machines, however, are limited in their applicability based on the shape of the parts. Electrocoating systems require a shift from solvent-based to waterbased paint. 

The utility of the bis cyclic ureas for curing of coatings was demonstrated by dispersing them in a functional acrylic polymer formulated for powder coating application, or by using them as additive in solvent based coatings or in aqueous polymer emulsions for electrocoating. 

Application of Topcoats Appliance Coating Specifications Recent Developments Flow Coat Conversion Electrocoating High Solids Powder Coatings Low Energy Cure Coatings Coatings to Replace Porcelain Future... 

Cationic electrocoating is now used on dryer drums, washer cabinets, and areas where superior corrosion resistance is required. Although cationic electrocoating is somewhat more expensive (10% higher than anodic), its advantages for certain applications justifies the higher cost. 

The majority of the currently used coating systems is based on copolymers prepared from epoxy resins, polyfunctional amines, and partially blocked isocyanates (84-87). The resins are generally solubilized by the formation of cationic derivatives of amines by aminolysls of the carbamate in the partially blocked isocyanate. The principal applications of these cationic electrocoating systems are as automotive primers, in appliances, as primers and one-coat system.s, and in various other industrial applications. The main... 

Acrylic cationic electrocoating systems employing blocked aliphatic isocyanates are finding application where a combination of excellent durability or light and color stability with corrosion resistance is desired, e.g., in agricultural implements (86). 

Anticorrosive Primers. Anticorrosive primers are applied in dip tanks so that they reach all parts of the car body dipping is a fast method of application. The standard method for application of primers is electrodeposition. Anodic electrodeposition paints were used when the electrocoating technique was first applied, but cathodic electrodeposition is now predominant because it provides better corrosion protection. 

The aliphatic amines are valuable intermediates for chemical synthesis applications, Reaction of ethylamine with cyanuric chloride yields triazine-type herbicides, Diethylamine is used in the preparation of vulcanization accelerators where reaction with carbon disulfide yields a dithiocarbamate. Triethyl-amine is used as an acid acceptor in chemical syntheses and as a salt former in various purification processes. The amine is used as a corrosion inhibitor in aqueous systems, as a catalyst in polyurethane applications, in textile and photographic applications, and in anodic electrocoating. 

For some applications, especially in the area of corrosion protection, electropolymerization of polyaniline onto active substrate is of interest. Lacroix and co-workers achieved this by first coating mild steel with a very thin PPy layer and then electrocoating polyaniline on top of this. Others have electrodeposited polyaniline-PPy composites on aluminum or steeP surfaces using oxalic acid electrolytes. A number of ring-substituted anilines have also been directly electrodeposited on active iron substrates using an oxalic acid electrolyte. To create novel nanostructures, polyanilines have been recently deposited on aligned carbon nanotubes or into the interstitial spaces of inverse opals to create novel ordered 3-D networks (Figure 4.2). Molecular templates (such as cyclodextrin) have also been added to electrode surfaces to facilitate electrodeposition of nanostructures. ... 

They give coatings with improved gloss and levelling. Hydrosols differ from latices with respect to particle size and the concentration of surfactant used in their manufacture, applications are in water thinned industrial finishes and electrocoating. 

The concept of electrocoating cans is not new, in fact it was mentioned as long ago as 1936(20) However, Metal Box pioneered the development of sophisticated equipment which could have made the concept a commercial reality In practice, the Metal Box electrodeposition system failed because of the problems of short circuits when the electrodes were inserted into the cans at the speeds required to enable economic can production. This development was complemented by the development of lacquer systems tailored for application by electrodeposition. 

The surge of interest in electrocoating cans has meant that the polymer chemist has had to learn how to formulate lacquers to meet a new set of parameters. Important factors in spray application such as low weight coverage, blister threshold and reverse wall failures no longer applied. The correctly formulated electrocoat lacquer deposits a uniform film over the can surface and is thrown onto the most difficult surfaces, like the reverse wall or beaded side wall, which may be in the shadow of the spray pattern from a spray gun fixed at the mouth of the can. Some of the important parameters in electrocoat are ... 

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